Grippers for containers, e.g., for bottles are used on container processing machines such as bottle processing machines for gripping the containers. In the gripped position, the containers can be processed. This may include applying or removing labels, coating, conveying, filling, sealing and the like.
Especially in handling PET bottles, such grippers are provided for gripping the bottles in their neck area with a collar provided for this purpose.
For example, a gripper with two swiveling levers which are linked for swiveling is known from EP 0 486 439 B1.
One disadvantage of this gripper is that the bottles can apply pressure to the gripper with forces corresponding to those that occur in the transfer of bottles, for example, with movement in the direction of the swiveling axes of the swiveling levers.
In addition, another disadvantage of this gripper is that it is suitable for only one bottle size.
SU 1 093 660 describes a gripper for objects having various diameters. A piston that can be moved back and forth is coupled to swiveling levers so that the piston together with the swiveling levers can stop objects of different sizes by coming to rest at three points, so that the centers of the various objects are always identically positioned.
The design of the piston that can be moved forward and in reverse and the type of coupling to the swiveling levers result in a great mechanical complexity and/or a great play, which leads to inaccuracies in holding the objects.
DE 199 03 319 A1 describes cells which may be of different sizes and can hold the bottles. A container is held at four points in the cell. A swiveling lever is provided for each point, the swiveling levers being linked together in various ways. One of the swiveling levers has an articulated lever which can be controlled by a cam.
Here again, the great mechanical complexity due to the four swiveling levers for the at least four points of contact between the bottle and the levers is a disadvantage. This complexity also results in a considerable play.